This is incredibly haunted, but it can happen that you change libutil,
breaking the generation of the .json files, which then does not rebuild
the files. I don't expect they are slow to build, so it does not seem so
bad to just rebuild them every time instead of extracting a list of all
the possible deps.
We want to delete this nonsense anyway and replace it with generated
code.
Change-Id: Ia576d1a3bdee48fbaefbb5ac194354428d179a84